Sequencing and phylogenetic analysis of vlhA gene from Mycoplasma synoviae field isolates associated with Eggshell apex abnormality

Eggshell apex abnormality (EAA) associated with Mycoplasma synoviae is occurring regularly in many commercial layer chicken farms of Tamil Nadu. Choanal cleft swabs were collected from EAA affected poultry farms, subjected for isolation and molecular detection of M. synoviae. Among 16 farms investigated M. synoviae could be isolated in six farms. All the farms were positive for M. synoviae in PCR. Among six isolates three isolates (VC&RI-NKL-SV3, VC&RI-NKL-PV6, VC&RI-NKL-KV2) from severe clinical outbreak were sequenced for vlhA gene and compared with the available sequences from the Gene Bank (NCBI) using multiple sequence alignments software-Clustal Omega and Bio edit programs. Analysis showed thattheVC&RI, NKL-SV3 and VC&RI-NKL-KV2were more similar (94.3%) to each other. Point mutation percentage of isolates VC&RI-NKL-PV6, VC&RI-NKL-SV3 and VC&RI-NKL-KV2 isolates in comparison with reference strain KC506806 were 12, 5.1 and 1.8% respectively. The phylogenetic analysis indicated that the VC&RI-NKL-SV3 and VC&RI-NKL-PV6 were closely evolved with VC&RI-NKL-KV2. VC&RI-NKL-KV2 was closely related to sequence of Mycoplasma synoviae from Brazil.